The present invention relates to a roll for a paper-making machine.
A number of rolls are used for making continuous paper at a high speed. In particular, 100 or more rolls, including several tens of dryer rolls, perforated suction rolls, blow-out rolls and the like, are used generally in a dryer part where the paper is to be dried.
FIGS. 7 and 8 show conventional examples of a roll arrangement of a dryer part in a paper-making machine. First of all, FIG. 7 shows an example of a single canvas dryer in which paper 17 and canvas 16 are always travelled together. The paper 17 is travels inside the canvas 16 on dryer rolls 13 so that the paper is pressed against the surfaces of the dryer rolls 13 by the canvas 16.
However, the paper 17 is travels outside of the canvas 16 on suction rolls 14. At this time, since the vacuum of the suction rolls 14 is applied to the paper 17 through the air-permeable canvas 16, the paper 14 travels under the condition in which the paper 14 is suctioned onto the canvas.
FIG. 8 shows an example of a double canvas dryer which is characterized in that a closed space, i.e. a so-called pocket 18, is surrounded by the dryer roll 13, the paper 17, the canvas 16 and a blow-out roll 15. Since this pocket 18 is insufficient in ventilation, hot air is blown into the pocket 18 through the air-permeable canvas 16 from the blow-out roll 15.
Incidentally, the perforated roll cells are used in both suction rolls 14 in FIG. 7 and blow-out rolls 15 in FIG. 8 in the same way.
FIGS. 3 and 4 show a conventional structure of a roll for a paper-making machine in which perforated roll cells are used. In FIGS. 3 and 4, reference character 1' denotes a roll cell coupled to roll heads 2, which in turn are rotatably supported by bearing housings 4 through bearings 3. Seal rings 9 and seal bars 10 are provided in a circumferential direction and in an axial direction, respectively, between a center shaft 5 and the roll cell 1' within the roll for effecting suction/blowing for a predetermined region. In FIG. 3, reference numeral 8 denotes a damper and numeral 11 denotes a center shaft head.
However, since the roll cell 1' is in contact with the seal rings 9 and the seal bars 10, the contact thereby causes a large friction/force against the rotation of the roll, increasing the rotational torque. Also, the conventional system suffers from a disadvantage in that vibration sounds are generated by the contact in accordance with the rotation of the roll, increasing the noises.
Furthermore, a roll structure having no center shaft has been conventionally proposed as shown in FIGS. 5 and 6. However, in this case, a sufficient suction cannot be attained due to the adverse effect of a centrifugal force caused by the rotation of the roll, or the suction/blowing for the predetermined region is non-uniform or otherwise cannot be attained. Reference numeral 12 denotes a baffle plate.
In order to overcome the conventional problems, an object of the invention is to provide a roll for a paper-making machine having a center shaft in which members which are to come into contact with the roll inner surface are dispensed with.